Per Stromgren wrote in message . ..
I remember some sub+satelite systems from the Swedish Dux and German
Braun, but that must have been earlier, probably late sixties. Both
units was mono sub if I am not mistaken (Svante, have you seen the Dux
units?), crossed over at some 150-200Hz.

Nope. My first contact with subs was DIY projects in various books and
magazines. I built my own first sub in the late 70's at age 16 or
something. It sounded wonderful... I thought. Those were happy,
ignorant days! My first contact with commercial subs was the Audio pro
B2-50.